Keith Foster and his girlfriend Pam are making out in his bed. She asks if he wants to do it, and Keith reluctantly agrees... to go driving in his father's new Porsche. Pam takes the car out while Keith sits in the passenger's seat, and she speeds down the road. At first, Pam doesn't notice that Keith is coughing up blood, until he spits on the mirror. Panicking, she skids the car and goes underneath a truck before braking to a halt. As she turns to check on Keith, a bus rams into them.
Later, Keith is admitted to the hospital and his father and Pam watch over him. Meanwhile, House is busy complaining to the pharmacist because the new shipment of Vicodin hasn't come in yet. The pharmacist checks and confirms that it'll take an hour to get the box rerouted to the right department. Cameron brings House Keith's file and explains that he's been bleeding internally for the last three hours. House would rather focus on something more important: getting Cuddy to expedite the Vicodin delivery. She isn't able to, and Cameron insists that Keith's hemolytic anemia is significant. House dismisses it as meningitis until Cameron proves it isn't. When House eliminates all the other obvious possibilities, he finally takes an interest and assembles the team. They disagree about the cause, and Foreman figures that it's environmental, and Keith will get better now that he's in the hospital. Cameron believes that it's lupus, and Chase suspects it's drugs. House tells all three of them to check out their theories and then goes off to get his Vicodin.
As House picks up his pills, Cuddy confronts him and insists that he's an addict. She warns that she can't protect him because people talk, but House assures her that he isn't addicted. She offers him a week off of clinic duty if he can go without Vicodin for a week, and House bargains her up to a month off. Cuddy gives in and agrees and House hands her the bottle.
Cameron checks with Mr. Foster about Keith's suspected drug use, and the father believes that Pam, who was in rehab, is giving Keith drugs. He also talks about how his wife died of cancer. Cameron, Chase, and Foreman check for drugs, infection, and any family history of lupus. When Mr. Foster notes that his wife died of pancreatic cancer, they call in Wilson to check Keith for lymphoma. As Wilson works, Keith wonders if he has anything to worry about. The oncologist says he doesn't, and the teenager notes that was what they told his mother before she died.
The team reports their findings to House, that everything was negative. House is beginning to show the strain of withdrawal, and Foreman wants to discuss it. However, they discover that Keith is going blind in his left eye. They find a retinal clot, but can't use blood thinners to break it up without making his internal bleeding worse. They have two hours to fix it before the damage is irreversible. When the team goes back into differential, House is surprised to discover that Wilson is there. He suspects that his friend is there to make sure House is adhering to his bet. When the team wonders what is going on, Wilson explains about the bet, and Foreman insists that House will go through a painful withdrawal. House insists that he's just tired, and that he won't go through withdrawal because he isn't an addict. He focuses on the case and the team suggests an infection in the heart. A clot in the heart broke off and blood flow took it to the eye.
As they discuss the case, House stares out into the hallway, where a young woman, Ingrid, is stretching. He tells them to test and to focus on the heart infection, not the eye, and then he and Wilson confirm that Ingrid is a masseuse. She uses acupuncture on House's hand, relieving his withdrawal pains temporarily, and then tells him to take off his clothes for a full massage.
Chase checks Keith's heart, and the boy realizes that their ignoring his eye problem to save his life, and that he will permanently lose his sight. Chase returns to see House as Ingrid leaves, and figures that she's a prostitute despite his boss' protestations. He reports that he couldn't find any heart infection, and the antibiotics aren't reversing Keith's bleeding. House tells him to double the dosage despite the risk to Keith's kidneys, but Chase suggests they save Keith's eye by draining off vitreous fluid from the left eye, allowing the artery to expand and free the clot. Impressed, House tells him to do it. Once Chase leaves, House staggers and leans against the wall for support.
Chase successful performs the operation, freeing the clot. Afterward, Pam comes to talk to Keith and worries that Mr. Foster blames her. As she starts to kiss him, Keith throws up on her, and they take him to ICU. Mr. Foster accompanies them and accuses Pam of giving Keith drugs. Chase argues that it's House's double-dosage of antibiotics that are causing the problem. A pale and sweating House, limping along, tells them that it's kidney failure. When Mr. Foster demands an explanation, House snaps at him. They almost come to blows until Foreman separates them. As they take the teenager on to ICU, Cameron pauses to tell House that he's being more insulting than usual and that the father had legitimate questions. House admits that he overreacted, and Cameron asks him if the month off of clinic duty is worth what he's going through.
While the team waits for House in the conference room, they argue about whether House is competent. Foreman wants to get House off the case to avoid ruining their reputation, Cameron defends her boss, and Chase figures that House can pull off a cure even in his current condition. House arrives and tells them to focus on the case, and Cameron insists that everything points to lupus. House disagrees, pointing out that it's moving too fast, and suggests that it's a rare case of Hepatitis E. The team disagrees, but House tells them to treat despite the risk. If he's wrong, Keith will get worse but slowly enough that they can switch to a different diagnosis. The others don't believe that Mr. Foster will okay such a dangerous and potentially useless treatment, and House tells Cameron to lie to the man because he trusts her. As the team leaves, Cameron insists that she doesn't want to lie. Foreman tells her to treat for lupus, but Chase warns that if she does, she'll be disobeying House and putting her job at risk. Foreman thinks that House's judgment is impaired, but Chase figures that their boss' long shots always pay off.
In his office, House picks up a pestle, contemplates it for a few seconds, and then slams it into his left hand. He moans in pain but then smiles with relief.
Cameron starts to lie to Mr. Foster about their treatment for Hep E, but he soon realizes that there are discrepancies in her story. When he talks about how the doctors gave his wife an experimental treatment but it simply killed her sooner rather than later, Cameron breaks down and tells him that he should let them treat for lupus.
House goes to Wilson to get his broken hand splinted, and lies about how it happened. Wilson realizes that House did it to temporarily neutralize the pain of withdrawal, and House insists that it worked. Cuddy comes in, having heard from Mr. Foster about Cameron's attempt to lie on House's orders, and warns that the father has told them to treat for lupus. She tells House to take a one-week leave of absence, but refuses and explains that all procedures are risky. The Hep E treatment is risky, but the knowledge they gain can save Keith's life. Cameron comes in and tells them that Mr. Foster has demanded that they take Keith to another hospital, but House figures that he caved and okayed the Hep E treatment once Cameron explained that Keith was in no condition to be moved.
As Chase and Cameron prepare to administer the Hep E treatment, Keith starts hallucinating, insisting that someone named Jules is attacking him. He then suffers from rectal bleeding and passes out. They determine that he's suffering from upper and lower GI bleeding and that his liver is failing. Cameron points out that the new symptom, hallucinations, is consistent with lupus, but a half-dazed House focuses on who Jules is. Cameron doesn't see the point of analyzing the hallucination, but House points out that it takes years for lupus to develop and Keith is too young. When she snaps at him, House explains that she's mad at him because she lied. When Cameron admits that she trusted House, he points out that was her mistake and insists that it's not lupus. However, they have nothing better for a diagnosis. They put Keith on the transplant list and ask Cuddy to try and influence the transplant committee to expedite delivery of a liver.
After the differential meeting, Foreman goes to House's office and finds his boss vomiting into a wastepaper basket. House insists that he's fine, but Foreman gives him a bottle of Vicodin and tells him to take it so that he won't kill the patient, and endanger Foreman's standing. As Foreman leaves, House dumps the pills on the desk and contemplates one.
Cameron tells Mr. Foster that they're treating for lupus and admits that House endangered Keith. Meanwhile, Cuddy is unable to get Keith moved up to the top of the transplant list. Mr. Foster tries to volunteer, but they explain that he has the wrong blood type. As they discuss the case outside of Keith's room, House staggers up and asks who Jules is. An exasperated Mr. Foster finally tells him that it's the family cat, which died some time ago. Since the cat is real, House insists that Keith had a psychosis, not an imaginary hallucination, disproving Cameron's theory of lupus. He demands to know what happened to the cat, and Pam explains that it died of what they believed was old age. House sends Foreman and Chase to dig up the cat, buried in the Fosters' backyard. They bring it back and House conducts a necropsy. Cameron watches from the shadows as House's hands shake.
Cuddy manages to get a liver for Keith and they prep for surgery. However, House finishes the necropsy and staggers into the operating room. He tells the surgeon, Dr. Hourani, that they have to stop the liver transplant because Keith's problem is that he's suffering from accurate naphthalene toxicity. The Foster home has termites, which give off naphthalene when making their nests. Hourani thinks that House is demented and refuses to stop the surgery, so House coughs in his face and spits on the surgery cloths, contaminating the OR and forcing the disgusted Hourani to stop the operation.
The team confronts House outside the OR and argues that they have to perform the surgery. When Foreman notes that it can't be environmental, House explains that naphthalene is fat-soluble. Keith's condition has worsened in the hospital because he lost weight due to the hospital food. The fat broke down, releasing the naphthalene into his bloodstream. Cuddy and Mr. Foster arrive, and the father immediately punches House. The immediate pain helps House overcome the withdrawal pains, and he explains that the necropsy revealed that Jules died of the same thing that Keith is dying of now. He warns Mr. Foster that if they remove the liver, Keith will die within 24 hours. The cure is to give the teenager high-fat food. Unsure of what to do, Mr. Foster turns to Cameron, who says that they should trust House. The father agrees and tells them to let the liver go to the next recipient.
Foreman and Chase go to the foster home and confirm that the place is infested with termites.
Forty-eight hours later, Keith has a full recovery and his liver recovers. Mr. Foster and Pam embrace Keith... together.
As the week ends, House boasts to Wilson that he would have taken two weeks off to beat Cuddy, and it was a piece of cake. Wilson doesn't believe that his friend's experience was as easy as he claims, and asks if he learned anything. House admits that he's learned that he's an addict, but insists that it's not a problem. He is able to function despite his addiction, and he needs the pills to overcome the pain in his leg. When Wilson asks if that's the only reason House takes Vicodin and points out that he's different since taking them, his friend insists that he's simply getting older and crankier. He takes the pills to stop the pain from his leg, and for no other reason.
Later, Cuddy comes to see Wilson as he leaves for the night. He explains that House believes he's a functional addict and doesn't have any other problems, and admits that his friend might be right. House warns that House won't be happy if he finds out the truth, but Wilson assures her that House will never believe that the bet was his idea.
In his office, House relaxes for the first time in a week, now that he's back on Vicodin.